1. Field of the Invention
The present invention generally relates to surgical sutures, and more specifically relates to sutures used for affixing prosthetic devices to tissue.
2. Description of the Related Art
Surgical sutures are used to close wounds and surgical incisions, and to repair damaged or severed muscles, vessels, and tissue. Typically, the suture is attached at one end to a needle, and the needle is drawn through tissue to form one or more loops holding the tissue together. The suture is subsequently tied off in one or more knots so that the tissue will remain drawn together.
Although sutures are very effective for closing wounds, there are a number of issues associated with using conventional sutures. Many of these issues are directly related to using knots to secure the sutures in place. If the knots are not tied properly, defects may arise including slippage, knot breakage, and re-opening of the wound.
In response to the obstacles associated with conventional sutures, barbed sutures have been developed. Unlike conventional sutures, barbed sutures have projecting barbs that allow the suture to be used to close wounds, approximate tissue, tighten tissue, and attach prosthetic devices—all without using knots. Fixing conventional sutures with knots requires the knots to be pushed down toward the tissue to assure proper tensioning and fixation of the sutures. In contrast, barbed sutures achieve proper tensioning and fixation by applying tension to the suture. For example, U.S. Pat. No. 5,931,855 discloses barbed sutures that are used for cosmetic procedures such as brow-lifts and face-lifts.
In some procedures, it is desirable to use barbed sutures to secure prosthetic devices such as bioprosthetic heart valves. For example, in certain embodiments of commonly assigned U.S. Patent Application Publication No. 2007/0005110, the disclosure of which is hereby incorporated by reference herein, braided barbed sutures are disposed in a heart valve sewing ring by first passing the sutures through an annulus and then passing the sutures through the valve sewing ring. First and second ends of the barbed suture may be passed through the openings of a pledget for securely seating the suture against the valve sewing ring. The pledget is typically positioned in a central region of the barbed suture, which is located between opposing sets of barbs. Approximately 12-20 sets of braided barbed sutures are used around the perimeter of the valve for securing the valve in place. The valve sewing ring is then parachuted down the sets of barbed sutures and seated in place within the annulus. After the sewing ring has been parachuted in a downward direction, the barbs prevent the sewing ring from being moved in the opposite, upward direction. The barbs hold the sewing ring in place without using knots.
In spite of the above advances, there remains a need for sutures, suture systems and suturing methods that more securely and reliably hold the sutures in place and minimize slippage of the sutures and/or the pledgets used in combination with the sutures. In addition, there remains a need for suture systems that simplify surgical procedures and minimize the likelihood of surgical error. There also remains a need for sutures that are able to more easily pass through tissue and sewing rings without causing damage.